Malaria is caused by a eukaryotic protist parasite of the genus Plasmodium. Transmission is typically by the bite of infected female Anopheles mosquitoes, which carry Plasmodium sporozoites in their salivary glands, though congenital transmission and transmission by blood transfusion is also possible. Within minutes after infection of a mammalian host, the sporozoites enter the blood stream and migrate to the liver, where they infect hepatocytes, mature and release thousands of merozoites. The parasites then enter the bloodstream, infecting red blood cells.
Malaria is a major health problem to residents and visitors in much of the tropics and subtropics, with 250 million cases of fever and approximately one million deaths annually (2005 WHO World Malaria Report 2008).